This invention relates to endodontic tools, and in particular, to a driver to vibrate an activator to enhance cleaning of root canals during an endodontic procedure.
Following tooth maturation, the dental pulp is harbored within the structural elements of the tooth. Frequently, and for a variety of reasons, the pulp is irreversibly injured, resulting in inflammatory and infectious conditions which often adversely affect the tooth and its supporting structures. Clinically, as an alternative to extraction, root canal treatment is performed and ideally directed towards the elimination of pulp, bacteria, and related irritants from the root canal system, followed by three-dimensionally filling the root canal space with an inert, biocompatible, dimensionally stable, filling material, such as gutta percha. Ideally, the obturation procedures will fill not just the main canal, but the fins, webs, cul-de-sacs, lateral canals, and all portals of exit between the root canal system and the tooth's attachment apparatus.
Central to a successful endodontic (or root canal) treatment has been the use of chemical reagents during mechanical root canal shaping procedures to completely clean all aspects of the root canal system. The chemicals used to enhance canal debridement and disinfection during cleaning and shaping procedures potentially reach all aspects of the root canal system. The most popular chemicals currently used during canal preparation to actively assist in cleaning and disinfecting include bleach, hydrogen peroxide, and chelating agents. Often, a 2%-5% solution of a clear, pale, greenish-yellow strongly alkaline solution of sodium hypochlorite (NaOCl) and ethylenediaminetetracetic acid (EDTA) are used.
During canal preparation, a solution of NaOCl is liberally irrigated into the root canal space where its solvent action facilitates the digestion and removal of pulp, bacteria, viruses, spores, endotoxins and other irritants generated by the microorganisms. This solution has the potential to circulate, penetrate and, hence, clean into all aspects of the root canal space. However, studies have shown that even the most thorough use of sodium hypochlorite does not remove all the material from the root canal. The walls of a root canal are comprised of dentin, which contains millions of dentinal tubules per square millimeter. Instruments used to negotiate and shape a canal cut dentin and dentin, in combination with organic substrates, forms dentinal mud. Dentinal mud, pulp, bacteria, and other related irritants have been consistently visualized histologically after cleaning and shaping procedures in the dentinal tubules and various aspects of the root canal systems. Thus, after cleaning and shaping procedures, the root canal is still covered with a film of debris, frequently described in the literature as a “smear layer.” This “smear layer” includes dentinal mud and/or organic debris, including the irritants noted above.
After cleaning and shaping, the root canal has been traditionally filled with gutta percha and a root sealer. However, if the smear layer or film is not adequately removed from the root canal, the smear layer can compromise the filling and sealing of the root canal system. If obturation is incomplete then the root canal space is predisposed to bacterial leakage and failure. Post-treatment failures attributable to leakage are common and require endodontic retreatment of the tooth or extraction. Thus, for a complete and thorough cleaning, this smear layer or film should be removed. To address the smear layer, practitioners use a weak acid or surfactant, such as 17% EDTA, in an effort to remove the smear layer. Typically, the root canal is flushed with EDTA, or other final rinse solutions, to accomplish this. Traditionally, some practitioners have used a metal root canal file or a cannula to activate the solution and enhance the performance of the EDTA. These devices may be used manually or mounted in an ultrasonic handpiece to produce vibrations and fluid movement. As an example, even when a file is used, it is impossible to ensure that the file is brought into contact with the complete surface of the root canal, and hence it is difficult to ensure that substantially all of the smear layer has been removed. Regrettably, the use of ultrasonically driven metal instruments has frequently led to iatrogenic events, such as broken instruments, ledges in the wall of the root canal preparation, or even perforation of the root canal. Hence the use of such instruments is not desirable.
U.S. Pat. No. 6,179,617 and Published U.S. application Ser. No. 20040214135, both of which are incorporated herein by reference, disclose an endodontic brush for use in removing the smear layer. A brush can work well to remove the smear layer from the main path of the root canal. However, the brush bristles may not extend into the fins, webs, cul-de-sacs, anastomoses, lateral canals, and portals of exit between the root canal system and the tooth's attachment apparatus. Hence, while the brush may effectively remove the smear layer from the main canal, these fins, webs, lateral canals, etc. may still contain pulp, bacteria and related irritants, which may then compromise sealing the canal.
Currently, ultrasonically activated endodontic instruments, are used, at times, to enhance the cleaning of a shaped canal prior to three-dimensional filling. Such instruments include, for example, the BUC® tips sold by SybronEndo, the ProUltra™ tips sold by Dentsply, and the CPR® tips sold by Obtura. These metal instruments are connected to an ultrasonic driver. The tips generally are contra-angled tips. For the ultrasonic energy to efficiently pass through the contra-angled portion and along the overall length to the tip, the instrument is required to be securely connected to the driver. To this end, these instruments are all connected to the drive by threads which require a wrench to fully and securely connect the instruments to the drive. Multiple tips may be used in a single procedure. As can be appreciated, the need to use a wrench to connect a tip to the driver and to then disconnect the tip from the driver increases the time involved in mounting and dismounting of the tips. Because these instruments oftentimes have abrasive coatings and additionally cut toward their tips, they should not be used to remove the smear layer.
I have found that by vibrationally driving a non-cutting activator, the cleaning solution can be made turbulent, inducing cavitation at the end of the activator and acoustic streaming along the length of the activator, thereby enhancing the removal of the smear layer from both a shaped root canal, and importantly, from the fins, webs, lateral canals, etc. commonly comprising root canal system anatomy.